1. Field of the Invention
This invention relates to an energy conserving moored buoyant ocean profiler
2. Description of the Prior Art
Profiles of temperature and salinity of the upper regions of the ocean are useful for the study of various ocean conditions.
In the Arctic the temperature and salinity of the near surface waters play a significant role in ice formation, movement and eventual decay with attendant climatic consequences. Hence it is desirable to collect data from this region. However, the ice presents a barrier to the collection of continuous long term data.
One approach to the collection of data is to utilize the ice as a supporting surface for suspending instruments. However, the ice is dangerous while it is forming, it usually does not remain stationary, and support is lost when the ice melts.
Another approach that one might consider is to install a subsurface mooring such that the subsurface float is positioned just below the underside of the ice when fully formed. However, the thickness of ice is difficult to predict and is not uniform. Furthermore, the bottom surface of the ice is usually jagged and can damage an instrument or supporting float that contacts it as the ice moves.
The problem of varying ice thickness could be overcome with the use of a winch and ice proximity sensor, such as sonar, to position the instrument to a safe distance from the ice underside. However, it is desirable to obtain data not only from one position immediately beneath the surface, but also from lower regions. Specifically, it would be desirable to be able to profile the top 50 meters, from a bottom point, which could be fixed, to an upper point immediately beneath the ice underside, which is variable due to the irregularity of the ice.
Obtaining profiles near the surface of the open ocean presents similar difficulties. Since the surface of the ocean is almost always in motion, mooring components at or near the surface are subject to oscillating forces that can lead to fatigue failure, and a storm can cause catastrophic failure.
Providing a profiling instrument for continuous long term data collection presents serious difficulties. The major problem is the energy required for raising and lowering the instrument. The instrument must be provided with buoyancy in order to maintain the mooring line in a near vertical position in water currents, and this buoyancy must be overcome by a force applied to the mooring cable by the winch. The energy required for a cycling system of raising and lowering such a buoyant member in a conventional manner, makes such a system impractical.
An object of the present invention is to provide a system of raising and lowering a subsurface instrument with little energy.
It has been found that an instrument can be raised and lowered to the desired position with little energy by a system utilizing buoyant members in a manner to store energy when the instrument is moved in one direction, to be recovered when moved in the opposite direction.
The present invention provides a moored ocean profiler comprising: a first buoyant member of relatively high buoyancy for mooring to the bottom of a water body by a first mooring line; first drive means associated with the first mooring line for raising or lowering the first buoyant member with respect to the water body bottom; a second buoyant member of relatively low buoyancy for carrying an instrument and attached to a second mooring line; second drive means associated with the second mooring line for raising or lowering the second buoyant member; means operatively interconnecting the first and second drive means such that the direction of travel is in opposite directions to one another, and whereby the ratio of travel distance of the first buoyant member with the travel distance of the second buoyant member is inversely equal to the ratio of the buoyancy of the first and second buoyant member, whereby the potential energy increase or decrease in one buoyant member is equal to the potential energy decrease or increase, respectively, in the other buoyant member; and means for controlling the first and second drive means.